I always thought Robby Krieger was underrated. At a time while most guitarists were just trying to out blues one another, he was coming up with really original stuff, mixing flamenco, pop, blues and jazz.
Antonio Forcione
Jimmy Page. Bit tongue in cheeck this one, but he cropped up on the other thread a fair amount as did Hendrix.
I think with these guys they opened doors and pushed boundaries, it's easy to look back and say some of their playing was sloppy but some of the people who don't get them seem to revere the guitarists who started from where they left off.
Noel Gallagher. Now I must be taking the P!ss. But unfortunately not. I think most choices seem to be based on guitar solos but having learned a lot of cover songs for gigs I'd have to say his songwriting and chord choices are very intresting. Solos as dull as dishwater but he can write a song. Now I'm not saying I'm a abig fan, but he is underatted